The present invention relates to apparatus and methods for inserting, retaining and extracting printed circuit boards from a housing and more particularly for inserting, retaining and extracting a printed circuit board wherein a relatively strong force is required, in addition to a high degree of accuracy in positioning the corresponding contacts.
As is known, printed circuit boards (PCBs) are a common form of electrical circuit packaging. Today, many electrical systems like computers, routers and switchers are based on a housing containing a backplane (circuit board) comprising active devices and at least one slot to connect a respective PCB (usually more than one PCB is connected to such a backplane). PCBs are linked to the backplane with connectors, located on the PCB""s lower edge and a corresponding backplane surface, through which signals are transmitted. These connectors must meet specific electrical and mechanical requirements, e.g., signals must be transmitted without deformation and at high speed. The PCBs must be able to be inserted and extracted relatively easily and must be retained so that necessary electrical connections are maintained.
A known mechanism to insert and extract PCBs from a housing consists of lever arms disposed on each upper side edge of the PCB which in turn cooperate with the housing. Such a mechanism is described in U.S. Pat. No. 4,914,552. The apparatus includes a lever mounted on the board and a cooperating gear assembly carried by the board and the housing for use in manually installing the board in, or removing the board from, the housing. A conventional locking wedge assembly can be manually operated by the same lever, to retain the PCB within the housing after its installation.
The present electronic packaging engineering practice is to increase the number of Input/Output (I/O) contacts (pins and sockets) for these structures, which in turn results in an increasing size for these PCBs. As a result, the mechanical packaging of these structures is more costly from both a development and manufacturing standpoint. As the number of electrical contacts increases, the force required to insert or extract a board from a housing increases correspondingly. Furthermore, the accuracy that is required in mating the connectors is more difficult to achieve because of the greater number of more closely positioned contacts that must be simultaneously made. In addition, each of the electrical contacts can be easily damaged by improper insertion. As a result, the effective installation and the removal of a PCB from such a backplane poses a significant engineering challenge.
It is believed, therefore, that an improved means for inserting and removing a PCB relative to a backplane would constitute an advancement in the art.
It is, therefore, a primary object of the present invention to provide an enhancement in the art of inserting and removing PCBs from backplane (and related) structures.
It is another object of the present invention to provide an apparatus that can withstand the relatively strong forces required to insert or remove a PCB in a housing including a backplane board therein.
It is another object of the invention to provide an apparatus for inserting or removing a PCB from a housing that provides a high degree of accuracy in aligning the mating electrical contacts.
The accomplishment of these and other related objects is achieved by an apparatus for positioning a PCB within a housing and for removing the PCB from said housing in which the PCB includes at least one connector positioned thereon and having a threaded opening therein. The housing includes a connector for coupling to the PCB connector. The apparatus comprises a a control shaft adapted for being rotatively moved in first and second opposing directions and at least one threaded shaft operatively coupled to the control shaft and adapted for being screwed into the at least one threaded opening in the at least one connector on the PCB during movement of the control shaft in the first direction to draw the PCB toward the at least one connector in the housing such that the at least one connector on the PCB will be electrically connected to the at least one connector within the housing, the at least one threaded shaft also adapted for being unscrewed from the at least one threaded opening during movement of the control shaft in the second direction to move the PCB away from the at least one connector within the housing such that the PCB will be disconnected from the at least one connector within the housing.
According to yet another aspect of the invention, there is provided a PCB having at least one connector positioned thereon along a lower edge of the PCB and including at least one threaded opening therein oriented substantially perpendicular to the lower edge.